1. Field of the Invention
The present invention relates to a sheet processing apparatus which applies a process such as a binding process to sheets, and an image forming apparatus having the sheet processing apparatus.
2. Description of the Related Art
Conventionally, in a sheet processing apparatus which applies a process such as staple binding to a sheet bundle on which images are formed by an image forming apparatus, there is a problem that throughput decreases when the process is applied. More specifically, a process operation, an operation of discharging from a processing portion a processed sheet bundle, and an operation of enabling the apparatus to receive the first sheet of a subsequent sheet bundle cannot be performed only in a period between sheet bundles upon continuous printing. Hence, between sheet bundles, it is necessary to provide a large interval between sheets by temporarily stopping to form images.
A configuration (U.S. Pat. No. 7,306,214) which makes some of first sheets forming a subsequent sheet bundle temporarily wait to buy some processing time and a configuration (U.S. Pat. No. 7,237,774) which enables a processing portion to receive a subsequent sheet bundle when a processed sheet bundle is discharged, are disclosed to solve this problem.
However, with a configuration disclosed in U.S. Pat. No. 7,306,214, a dedicated conveying path, conveying portion and driving portion which make the first page of a subsequent sheet bundle temporarily wait are required, and this makes apparatuses larger and more costly.
Further, with the configuration disclosed in U.S. Pat. No. 7,237,774, when the first page of a subsequent sheet bundle is conveyed, the discharging lever must be retracted, and, accompanying speeding up of image forming apparatuses, a bundle discharging process is not performed on the right time between sheet bundles, causing the decrease in throughput.
Therefore, the present invention provides a sheet processing apparatus and an image forming apparatus having this sheet processing apparatus which enables a processing portion to receive some of the first sheets of a subsequent sheet bundle during a process operation and a discharging operation, and which can prevent the decrease in throughput while preventing the apparatus from becoming larger size and more costly.